JP2009131900A - Hotplate with lifting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a hotplate capable of simultaneously lifting a workpiece arranged on the hotplate for the entire area of the workpiece in contact with the hotplate by using a simple means. <P>SOLUTION: The hotplate for a workpiece comprises a heatable plate 2 which on a first side comprises a support surface 2.1 for the workpiece, several lifting elements 15 for the lifting of the workpiece relative to the support surface 2.1, wherein each lifting element 15 is movably arranged in such a manner that each lifting element 15 can be retracted with respect to the support surface 2.1 and/or extended with respect to the support surface 2.1 and means for heating the plate. The means for heating comprise at least one heating channel 20 which extends on a second side 2.2 of the plate 2 located opposite the support surface 2.1 and is filled with a heating fluid. The heating fluid is in contact with the plate 2. The lifting elements 15 are loaded with the heating fluid in such a manner that the lifting elements 15 are extendable through a predetermined change p-p<SB>0</SB>of the hydrostatic pressure p of the heating fluid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heating plate with a lifting element for lifting a workpiece heated by the heating plate against a hot plate.

  This type of hot plate is more preferably used in a laminating press that produces a photovoltaic module.

  During lamination, a thin, usually thin film, layer is combined with the carrier material. In many cases, for example, in the production of photovoltaic component assemblies, it is necessary to perform this lamination process at a high temperature (hot lamination). At this time, the workpiece to be processed (that is, the carrier material covered with the layers to be joined) is generally heated to a predetermined temperature on the support surface of the heating plate and then pressed.

  In this lamination process, it is important that the temperature distribution on the support surface of the heating plate is as uniform as possible. Furthermore, it must be possible to temporarily interrupt the heat supply, which can be achieved, for example, by lifting the workpiece against the support surface. For some applications, the lamination process is performed in a vacuum. For this type of application, it is practical to place and operate the heating plate in an evacuable chamber.

  From EP 0 678 357 A1, for example, a laminating press with a heating plate arranged in an evacuable chamber is known. Each of the heating plates is disposed in a vertical guide hole of the heatable plate. The heating plate also includes a plurality of lifting elements that are extendable from the respective guide holes beyond the support surface of the plate so that the workpiece can be lifted relative to the support surface. Each lifting element is extensible using a pneumatically actuable piston located in a cylinder that extends into the plate under the support surface. To actuate each piston, the pressure difference between the evacuable chamber and the environment is utilized, and when a vacuum is generated in the chamber, all lifting elements covered by the respective workpiece are automatically Lifted to. This heating plate has several disadvantages. Because of the many cylinders that must be made inside the plate for the piston, the manufacture of the heating plate is expensive. Furthermore, the plurality of cylinders and the airflow generated when operating the cylinders results in a non-uniform temperature distribution in the area of the support surface. Furthermore, the lifting of the workpiece is connected to the standing of the vacuum in the chamber. Thus, the time available for heating the workpiece cannot be selected independently from the standing of the vacuum and therefore cannot be freely selected. A further disadvantage will be found in that the pneumatic actuation of the piston makes it more difficult to lift the lifting elements simultaneously. In order to lift the lifting element simultaneously, the lifting element and the piston can be connected to each other. This will make the manufacture of the heating plate even more expensive.

  From EP 1550548 A1 a further laminating press with a hot plate arranged in an evacuable chamber is known. The heating plate is disposed away from the base portion of the chamber and includes a plurality of vertical holes. In order to be able to lift the workpiece resting on the heating plate, a plurality of lifting devices are provided, each consisting of a pin and a drive for each pin. The drive is individually placed on the base of the chamber below the heating plate so that each pin can be guided or extended through a hole in the heating plate. For example, a pneumatic cylinder or a mechanical drive is provided as the drive. This configuration of heating plate and lifting device is also associated with several disadvantages. On the one hand, since there are a large number of drive devices, expensive means, in particular means for sealing the drive device and the chamber, are required to be able to operate and control the drive device in a vacuum. Further, particularly in the case of relatively large plates and a large number of lifting devices, the assembly of the lifting device and the heating plate is expensive. Furthermore, the maintenance of the drive device is more difficult, and it is more difficult because it is not easily accessible under the plate. Furthermore, due to the large number of drives, stretching all the pins at the same time results in considerable expense and is more expensive because all the drives must be synchronized.

  The present invention avoids the disadvantages described above, produces a temperature distribution that is as uniform as possible in the region of the support surface of the heating plate, and uses simple means to replace the workpiece placed on the heating plate with the heating plate. Based on the purpose of producing a heating plate that allows the entire area of the workpiece in contact to be lifted simultaneously.

  This object is solved by a heating plate with the features of claim 1.

  The heating plate includes a heatable plate having a support surface for a workpiece on a first surface and a plurality of lifting elements for lifting the workpiece relative to the support surface, each lifting element on the support surface. A lifting element movably arranged to be retractable relative to and / or to the support surface and means for heating the plate.

  According to the invention, the means for heating the plate comprises at least one heating channel extending on the second side of the plate located opposite the support surface and filled with heating fluid, Is in contact with the plate and the lifting element is loaded with the heating fluid such that the lifting element is stretchable by a predetermined change in the hydrostatic pressure of the heating fluid.

  “Heating fluid” in this context is considered any fluid that can release heat to the plate, for example, a fluid that is heated using a heating element.

  Since at least the plate near all lifting elements on the side opposite the support surface is in contact with the heating fluid, a requirement is given that uniform heating of the plate can be achieved. Where applicable, the heated fluid can circulate in the heated flow path, thereby providing a balance of temperature variations. In order to optimize the respective temperature distribution, the lifting elements can be distributed as evenly as possible over the entire support surface. Thus, the heating channel can be properly positioned relative to the lifting element and can be optimized with respect to the size of the contact area between the plate and the heating fluid.

  Since the heating fluid must be considered incompressible (compared to gas), all lifting elements loaded with heating fluid in the heating channel will change the hydrostatic pressure of the heating fluid Can be stretched simultaneously irrespective of the number of lifting elements and the size of the heating plate. In this way, the workpiece placed on the heating plate can be lifted simultaneously for all areas of the workpiece that are in contact with the heating plate. In particular, since only one parameter (hydrostatic pressure of the heated fluid) has to be changed, it is easily achievable to stretch or contract all lifting elements simultaneously. The appropriate change in hydrostatic pressure can be controlled using simple means, for example using a conventional pump, or by mechanical movement of the heated fluid.

  In one embodiment of the heating plate according to the invention, each lifting element is arranged in a guide hole passing through the plate, the guide hole terminating in the heating channel. The lifting element comprises a piston and can be arranged such that at least one piston surface is in contact with the heated fluid. In this embodiment, the piston or lifting element can be sealed with a sealing element for each guide hole in which the lifting element is placed.

  Further embodiments are each insertable into a flow path through the plate and comprise one or more lifting elements and a support structure with a guide hole for each lifting element, Based on a replaceable component assembly in which the support structure can be inserted into the flow path. This component assembly is feasible so that each component assembly can be exchanged as a whole from the support surface of the plate. This facilitates maintenance and repair of lifting elements and other replaceable components, if applicable.

  In a further development of this embodiment, it is provided that each lifting element comprises a piston having a piston surface that is loaded with heated fluid. The piston can also protrude into the heating channel.

  The component assembly described above simplifies sealing against heated fluid. Forming a connection between the lifting element or the piston and the support structure so that the guide hole for each lifting element is sealed against the heated fluid, for example using a deformable sealing element The piston can be sealed (for example, using a flexible bellows made of metal). Such a sealing element can be attached to one side of the support structure outside the guide hole and the other side on the lifting element or piston so that heated fluid cannot enter the guide hole. is there.

  In this case, the lifting element and the wall of the guide hole are arranged in the guide hole so that the sealing element has to slide with respect to the lifting element during movement of the lifting element or with respect to the guide hole in the plate. There is no need to arrange a sealing element between. In addition to the proximity of the heated fluid, a sliding sealing element between the two parts moved relative to each other, which can be subject to severe fluctuations in temperature and pressure, is not required in this case. In particular, it is possible to omit rubber seals that can be overloaded by large fluctuations in temperature and pressure.

  Each lifting element is connectable with a preloaded spring element such that when the hydrostatic pressure of the heated fluid is below a predetermined value, the lifting element is contracted with respect to the support surface. The preloading of the spring element ensures that the lifting element is deflated at a low hydrostatic pressure and can assume a stable equilibrium position. Thus, a force that exceeds at least the preload of the spring element is required to extend the lifting element. This construction is particularly advantageous for the use of hot plates in a vacuum. When the hydrostatic pressure drops below a predetermined value, the spring element is preliminarily so that the lifting element contracts with respect to the support surface by using a predetermined pressure in the vicinity of the heating plate (outside the heating flow path). The load is always selectable.

  The arrangement of the heating channel on the surface of the plate opposite the support surface of the plate provides the advantage that a hole penetrating the plate need not be provided to realize the heating channel. In order to realize the heating channel, a two-part structure is recommended in which the heating channel on one side is limited by a plate and the opposite side is limited by a wall attached to the plate. Each connection between the wall and the plate is generally feasible using conventional means so as to be sealed against the heated fluid. This allows cost-effective manufacturing of each heating channel.

  Further details of the present invention and more preferred exemplary embodiments of the present invention are described below with reference to the accompanying drawings.

  1-3 show various views of a heating plate 1 according to the present invention. The heating plate 1 comprises a heatable plate 2 with a flat support surface 2.1 for the workpiece to be heated on the first surface (top).

  In the region of the surface 2.2 formed on the second (lower) surface located on the opposite side of the support surface 2.1, the plate 2 comprises a heating channel 20 filled with a heating fluid. As shown in FIG. 1, in the case of the details of the heating plate 1 shown in FIG. 1, the heating channel 20 is composed of a plurality of portions that run parallel to each other and have a distance from each other. Such portions can be arranged distributed over the surface 2.2 and connected to each other at various points so that heating fluid can be circulated throughout the heating channel 20.

  In this case, the surface 2.2 is a flat surface. The heating channel 20 is limited on one side by the area of the surface 2.2 and on the other side in this case by a wall 21 consisting of a molded part with a trapezoidal profile. The exact shape of the outline is not meaningful in this context. It is only important that the heated fluid is in contact with a partial area of the surface 2.2 that is large enough to ensure a limited heat flow within a predetermined tolerance range.

  The wall 21 is connected to the plate 2 at two edges 21.1 so that the heating channel is sealed against the heating fluid in the region of the edges 21.1. The wall 21 may be a sheet metal structure, for example. The wall 21 can for example be welded to the plate 2 at the edge 21.1. Alternatively, the wall 21 can be screwed to the plate 2 and sealed if necessary.

  As shown in FIGS. 1 to 3, the heating plate 1 in the region above the heating channel 20 includes a plurality of component assemblies 10 inserted into the channel 2.3. The channel 2.3 passes through the plate 2 and terminates at the surface 2.2 of the heating channel 20.

  Each component assembly 10 comprises a support structure 11 with a guide hole 11.1 for a lifting element 15 formed in the center of the support structure 11. The channel 2.3 is such that the support structure 11 of the component assembly 10 is securely attached to one of the channels 2.3 and is inserted into the respective channel 2.3 from the support side 2.1 of the plate 2 It is possible and is formed so that it can be attached to the plate 2 using removable fasteners 12 (eg screws). As shown in FIGS. 1 to 3, when each component assembly 10 is inserted into the flow path 2.3, the upper end of the support structure 11 is flush with the support surface 2.1. Become. As shown in FIG. 2, each support structure 11 can be sealed to the plate 2 using an O-ring 13.

  2 and 3, the guide hole 11.1 is a hole that passes through the support structure 11 and runs perpendicular to the support surface 2.1.

  The lifting element 15 has a slightly longer pin 15 with one end guided into the guide hole 11.1 in the length direction of the guide hole 11.1 and the opposite end protruding into the heating channel 20. .1 and a piston 15.2 seated on this opposite end of the pin 15.1 and securely connected to the pin 15.1.

  As shown in FIGS. 2 and 3, each lifting element 15 can move in the length direction of the guide hole 11.1. According to FIG. 2, the lifting element 15 can be extended from the guide hole 11.1 by a predetermined stroke. This stroke is limited because the support structure 11 forms a mechanical stop for the piston 15.2. Therefore, the maximum stroke is reached when the piston 15.2 hits the support structure 11 (FIG. 2). As shown by FIG. 3, the lifting element is movable in the opposite direction (ie in the direction of the heating channel 20) until the conical head of the lifting element hits the support structure 11. In this position, the lifting element 15 is retracted into the guide hole 11.1 so that the edge of the head of the lifting element 15 is flush with the support surface 2.1 (FIG. 3).

  The piston 15.2 projects into the heating channel 15 and is loaded by the heating fluid. It is therefore possible to move the piston 15.2 and thus the lifting element 15 by changing the hydrostatic pressure p of the heated fluid.

  1 and 2, the piston 15.2 is connected to the support structure 11 by a deformable bellows, preferably by a metal bellows 17. The bellows 17 seals the guide hole 11.1 against the heated fluid. The bellows 17 can further be configured such that the bellows 17 pushes the lifting element 15 into the contracted state according to FIG. 3, so that the bellows 17 can be preloaded in the length direction of the pin 15.1. . Furthermore, a spring element 18 (coil spring) is arranged between the support structure 11 and the piston 15.2 so as to receive a compressive load. Under this circumstance, the spring element 18 pushes the lifting element 15 further into the contracted state.

The preload of the bellows 17 and the spring element 18 is selected such that when the hydrostatic pressure p of the heated fluid is lower than the predetermined value p ₀ , the lifting element 15 is contracted against the support surface 2.1 (FIG. 3). The If the hydrostatic pressure p exceeds the value p ₀ by a predetermined difference Δp, the lifting element 15 reaches the maximum stroke and assumes an extended state (FIG. 2).

  FIG. 4 is formed on a plate 30 having a support surface 30.1 for a workpiece with a plurality of component assemblies 10 and on a surface 30.2 of the plate 30 located on the opposite side of the support surface 30.1. A further example of a heating plate according to the invention comprising a heated heating channel 20 is shown. Compared with the embodiment according to FIGS. 1 to 3, the heating channel 20 is formed in a channel hole located in the face of the plate 30 located on the opposite side of the support surface 30.1 and is covered by a wall 31. Compared to the wall 21, the wall 31 is flat.

  The exemplary embodiments shown in FIGS. 1-4 can be varied in many ways. The support surfaces 2.1 and 30.1 are not necessarily flat, for example. The heatable plates 2 and 30 can also comprise a plurality of heating channels 20 that are spaced apart from each other. It is also conceivable that each of the various partial areas of the support surface comprises a lifting element that can be extended over a distance of different lengths relative to the respective support surface.

It is a perspective view which shows the detail of one Example of the heating plate by this invention. 2 shows a section through the lifting element of the heating plate according to FIG. 1, shown with the lifting element extended. FIG. FIG. 2 shows a section through the lifting element of the heating plate according to FIG. 1, shown with the lifting element contracted. It is a perspective view which shows the detail of another Example of the heating plate by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating plate 2 Heatable plate 2.1 Support surface 2.2 Surface 2.3 Flow path 10 Component assembly 11 Support structure 11.1 Guide hole 12 Fastener 13 O-ring 15 Lifting element 15.1 Pin 15. 2 Piston 17 Bellow 18 Spring element 20 Heating flow path 21 Wall 21.1 Edge 30 Plate 30.1 Support surface 30.2 Surface 31 Wall

Claims (10)

A heating plate (1) for a workpiece,
A heatable plate (2, 30) comprising a support surface (2.1, 30.1) for the workpiece on a first surface;
In a plurality of lifting elements (15) for lifting the workpiece relative to the support surface (2.1, 30.1), each said lifting element relative to the support surface (2.1, 30.1) Lifting elements in which the respective lifting elements (15) are movably arranged so as to be retractable and / or extendable with respect to the support surface (2.1, 30.1) (15) and
Means for heating,
The heating means extends on a second surface (2.2, 30.2) of the plate (2, 30) located on the opposite side of the support surface and is filled with a heating fluid, at least Comprising one heating channel (20), wherein the heating fluid is in contact with the plates (2, 30);
As it can be extended by the lifting element (15) a predetermined change in hydrostatic pressure (p) of the heating fluid (p~p _0), that the lifting element (15) is subjected to load by the heated fluid A heating plate (1) characterized by   2. A heating plate according to claim 1, wherein each lifting element is arranged in a guide hole through the plate, terminating in the heating flow path.   3. A heating plate according to claim 1 or 2, wherein each lifting element comprises a piston face that is loaded with the heating fluid.   Comprising at least one replaceable part assembly (10) inserted in a flow path (2.3) passing through said plate (2, 30), said part assembly (10) being at least one lift A support structure (11) having at least one guide hole (11.1) for the element (15), the lifting element (15) being arranged in each guide hole (11.1), The heating plate according to claim 1, wherein a body (10) is insertable into the flow path (2.3).   The heating plate according to claim 4, wherein the lifting element (15) comprises a piston (15.2) loaded by the heating fluid.   A deformable seal forming a connection between the piston (15.2) and the support structure (11) such that the guide hole (11.1) is sealed against the heated fluid. 6. A heating plate according to claim 5, comprising a stop element (17).   The heating plate according to claim 6, wherein the sealing element (17) is a metal bellows. When each said lifting element (15) has said hydrostatic pressure (p) of said heated fluid lower than a predetermined value (p ₀ ), said lifting element (15) becomes said support surface (2.1, 30.1). A heating plate according to any one of the preceding claims, connected to a spring element (17, 18) preloaded so as to be contracted against).   The heating fluid in the heating channel (20) is subjected to the second surface area (2.2, 30.2) of the plate (2, 30) and the wall (21, 31) attached to the plate. The heating plate according to any one of claims 1 to 8, which is surrounded by   The heating plate according to claim 9, wherein the walls (21, 31) are welded together with the plates (2, 30).

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